The proposed research is to determine if stress (electrical, thermal) can modify communication involving opioid neuropeptides between the immune and nervous system. The study will attempt to monitor cellular conformational changes of invertebrate immunocytes and human leukocytes, by way of image analysis, for their responsiveness to opioid challenge. Additionally, high affinity opioid binding analysis will be performed on both cell populations to correlate binding efficacies with the conformational changes to determine opioid receptor subtype. This analysis will provide detailed knowledge that at present is lacking concerning this communication. Once this base line information is obtained, it will be analyzed for its significance in how Mytilus (Bivalvia) handle thermal and physical stress by way of the endogenous opioid-immune system. Previous work demonstrates that this opioid-immune-stress relationship in Mytilus is quite similar to that which is found in mammals. Lastly, "stress-activated" cells will be transplanted into non-stressed animals to determine if this state of alertness can be transferred, indicating a chemical messenger (opioid). Both physiological and behavioral parameters (presynaptic dopamine release and ciliary activation) will be monitored to determine if the "activated hemolymph and/or cells may modify ciliary regulation, thus, behavior. This bidirectional communication mechanism may partially account for cognitive and noncognitive influences on behavior. To date, little work has been performed on the cellular and molecular level in determining the mechanisms whereby stress can modify the functioning of these systems and in turn behavior. Indeed, if stress can modify immune function which is then transmitted to the CNS we may be developing a model of some mental disorders based on the sensing ability of the immune system. Furthermore, the detailed analysis of the opioid effects on the immune system has biomedical significance in the treatment of substance abuse since the sensing as well as the immune system may be compromised. The study will utilize undergraduate minority students as research assistants.